The present invention relates to a fastener assembly, and in particular to a fastener assembly including a nut with an enlarged head and an internally threaded shank with an encapsulating plastic layer protecting the enlarged head of the nut. An externally threaded screw is received in the internally threaded shank of the nut.
It is known in the art to encapsulate fasteners with some type of a plastic covering. Such covered heads are disclosed in U.S. Pat. Nos. 73,088; 563,969; 1,941,175; 1,867,354; 3,470,787; 3,693,495 and 4,293,243. Other types of covered heads are disclosed in U.S. Pat. Nos. 3,134,290; 4,316,690; 4,373,842; and 4,482,278. An encapsulated head, barbed shank fastener is disclosed in U.S. Pat. No. 5,244,326, the disclosure of which is incorporated herein in its entirety. A closed-end ridged neck threaded fastener is disclosed in U.S. Pat. No. 5,244,326, the disclosure of which is incorporated herein in its entirety.
Fastener assemblies including a nut with an enlarged encapsulated head have an internally threaded shank comprising a blind hole. The screw is threaded into the blind hole to secure the two fastener parts together and to clamp the fastened pieces together.
In some uses of encapsulated fastener assemblies, such as in the construction of wall panels for truck bodies, stronger, lighter and thinner materials are being used which have been posing problems for existing fasteners. As the panels and extrusions to be joined together become thinner, their combined thickness becomes smaller than the length of the screw of the fastener assembly, which has a predetermined minimum length due to fabrication limitations. This causes the screw to protrude through the surface of the materials being joined. When this occurs, the screw cannot be tightened completely into the nut because the screw bottoms out on the bottom of the blind hole in the nut before the head of the nut and the head of the screw tightly clamp the plies of the panels together.
A solution of using washers or other spacers under the head of the nut to hold the head of the nut away from the surface that the screw protrudes through not only increases the parts costs, but also the labor time and cost for assembly. Further, the use of washers or spacers can reduce the effectiveness of the liquid seal provided by the encapsulating head of the nut.
Consequently, it can be seen that the need exists for a fastener assembly that can provide an encapsulated head for a nut and yet be used in a thin wall assembly.